Major Customers (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue, Major Customer [Line Items]
Total sales	$ 46,124,000	$ 34,681,000	$ 87,199,000	$ 69,043,000
Total product sales	43,317,000	32,146,000	83,981,000	65,004,000
Total tooling sales	2,807,000	2,535,000	3,218,000	4,039,000
Navistar [Member]
Revenue, Major Customer [Line Items]
Total sales	13,958,000	12,540,000	26,671,000	24,807,000
Volvo [Member]
Revenue, Major Customer [Line Items]
Total sales	12,759,000	1,391,000	23,005,000	3,137,000
Paccar [Member]
Revenue, Major Customer [Line Items]
Total sales	8,568,000	12,590,000	16,960,000	24,061,000
Yamaha [Member]
Revenue, Major Customer [Line Items]
Total sales	4,228,000	2,907,000	9,228,000	6,914,000
Other Customers [Member]
Revenue, Major Customer [Line Items]
Total sales	6,611,000	5,253,000	11,335,000	10,124,000
Product Sales [Member] | Navistar [Member]
Revenue, Major Customer [Line Items]
Total sales	13,919,000	11,980,000	26,621,000	24,218,000
Product Sales [Member] | Volvo [Member]
Revenue, Major Customer [Line Items]
Total sales	11,781,000	1,391,000	21,856,000	2,560,000
Product Sales [Member] | Paccar [Member]
Revenue, Major Customer [Line Items]
Total sales	8,484,000	11,030,000	16,671,000	21,852,000
Product Sales [Member] | Yamaha [Member]
Revenue, Major Customer [Line Items]
Total sales	4,228,000	2,907,000	9,228,000	6,914,000
Product Sales [Member] | Other Customers [Member]
Revenue, Major Customer [Line Items]
Total sales	4,905,000	4,838,000	9,605,000	9,460,000
Tooling Sales [Member] | Navistar [Member]
Revenue, Major Customer [Line Items]
Total sales	39,000	560,000	50,000	589,000
Tooling Sales [Member] | Volvo [Member]
Revenue, Major Customer [Line Items]
Total sales	978,000	0	1,149,000	577,000
Tooling Sales [Member] | Paccar [Member]
Revenue, Major Customer [Line Items]
Total sales	84,000	1,560,000	289,000	2,209,000
Tooling Sales [Member] | Yamaha [Member]
Revenue, Major Customer [Line Items]
Total sales	0	0	0	0
Tooling Sales [Member] | Other Customers [Member]
Revenue, Major Customer [Line Items]
Total sales	$ 1,706,000	$ 415,000	$ 1,730,000	$ 664,000